//console.log('你好');
//alert(220+230);
//alert(2 * 3 + 8 / 2 - 1);

//一个等号是赋值，两个等号是判断，三个也是
//alert(22 == 22);
//alert(22 > 33);

//以拼接的形式呈现
//alert("123"+"123")
//以运算的形式呈现
//alert(123+123)

//中文、字母：字符串
//alert("hello")
//alert('hello')

//数字：用引号包起来，字符串，不用引号抱起来就是纯数字
/*
alert('123')
alert("123")
alert(123)*/
//
//console.log("小明" == "amdin")
//console.log("123" == "123")

//alert('123'+'123');
//alert('123 + 123 =' +  123 + 123);
//alert('123 + 123 =' +(123+123));
//alert('245 + 398 =' + (654+541))

//if(22>33){
//    alert("ture")
//}else{
//    alert("falce")
//}

//function sum(a,b){
//    var c = a + b;
//    return c;
//}
//alert(sum(10,20));
//alert(sum(20,30));

//function num(a){
//    alert(123);
//}
//num();
//num();

//function num(a){
//    alert(a);
//}
//num(100);
//num(200);

//function num(a,b){
//        alert(a * b + a / b);
//}
//num(100,200);
//num(200,300);

//console.log(document);
//document.getElementById("text");
//console.log(document.getElementById("text").innerHTML);
//
//var text =document.getElementById("text");
//console.log(text.innerHTML);
//text.innerHTML = "我使用js修改了hello！";
//
//var nav =document.querySelector("nav");
//console.log(nav);
//nav.innerHTML ="1";
//
//var banner =document.querySelector(".banner");
//console.log(banner);
//banner.innerHTML ="2";
//
//var footer =document.querySelector("#footer");
//console.log(footer);
//footer.innerHTML ="3";
function color(a){
    document.querySelector("body").style.background=a
}
function div(b){
    color(b.value)
}
function dic(b){
    color(b.value)
}
